This invention relates to flow cytometers which are designed for repetitive processing of substances. Specifically, the invention relates to systems which repetitively introduce samples without contamination for high speed processing. It is particularly suited to sorting and analysis applications in both the clinical and research fields.
Flow cytometers have been in clinical and research use for many years. Basically, the systems act to position small amounts of a substance within a sheath fluid. This sheath fluid may either form droplets or may exist within a transparent channel for optical analysis. Through hydrodynamic focusing and laminar flow, the substance is split into individual cells and the like and is surrounded by a sheath fluid. Since individual cells and the like are often processed, the speed at which substance material can be processed is somewhat limited.
In many applications the substance involves a liquid which is frequently changed. This may include processing a sample from one patient to another. These changes further limit the speed at which processing may occur. Further samples tested can also involve biologically active materials such as viruses and the like. This can intensify the need to thoroughly clean and decontaminate the system when changing samples.
In use, it is typical to receive sample substances as liquids contained within test tubes. These test tubes are attached or inserted into a flow cytometer system which pressurizes the test tube and thus forces the substance through tubing and into a nozzle container of the flow cytometer. For convenience, the test tubes are often attached by inserting a stopper into the test tube top. These stoppers often had two tubes positioned through them: a tube for supplying pressure to the test tube and a tube for allowing the substance to flow out of the test tube. As indicated in U.S. Pat. No. 5,182,617, a variety of designs have been proposed to facilitate more rapid processing. These designs have, however, not totally met the needs of those involved in the actual processing of samples.
One of the problems faced has been the stresses placed upon the test tube or other container as it is pressurized for use. Because of the relationship between the speed of processing and the pressure applied to the sample container, this problem is intensified as higher processing speeds are pursued. While naturally other containers other than a test tube could be used, the time required to transfer substance to some more appropriate container and the additional decontamination potentially required has made such solutions generally undesirable. In some applications, those involved have simply utilized the conventional components closer to their inherent limitations and may have even limited the performance of the flow cytometer to accommodate such limitations. Obviously, such an approach, although practical, is undesirable.
Yet another problem faced by those skilled in the art is the fact that the proper combination of features and performance for practical use of a flow cytometer for repetitive sampling of substances has not yet been achieved. Apart from the actual analysis capability of the flow cytometer, it is necessary to provide a system which those involved in the actual usage of the system find convenient. For some applications, this involves providing a system which can be easily cleaned or decontaminated between sample runs. In others an easily manipulatable and inexpensive system may be desired. The present invention combines features to achieve a practicably implementable system which meets each of these needs (and other needs more appropriately).
As mentioned, when biologically active materials are used, the problem of contamination is of greater concern. Not only has this mandated more thorough cleaning of the system between uses, but it also has made the problem of aerosols more acute. As pressure is applied to the sample container, this pressure--and the air flows associated with it--can result in the creation of aerosols which may contain a biologically active substance. Naturally, this must be avoided. Through potentially independent features, the present invention acts to minimize the creation of the aerosols in the first place.
As explained, a number of the foregoing problems have long been recognized by those having ordinary skill in the art. Solutions, however, have not been achieved in a practical and efficient manner even though the implementing arts have long been available. To some extent, this may be due to the fact that those having ordinary skill in the art may not have fully appreciated the nature of the problems or may have simply failed to consider designs which could be practically adapted to traditional components. Indeed, the directions taken by those skilled in the art have to some degree been directed away from the directions taken in the present invention. Until the present invention a system which simultaneously met the needs for high speed processing for changing samples, for cleaning the system, and for avoiding contamination was not practically available for many applications.